Philadelphia’s Biosolids Recycling Center
Prior to 1980, Philadelphia wastewater was dumped directly into the surrounding bodies of water, from which the population took its drinking water and bathing water. The wastewater consisted of liquid waste that came from the residents of Philadelphia, as well as industrial, commercial and agricultural sites. This kind of negligence caused the spread of disease to Philadelphia’s residents through unsanitary living conditions and polluted water. In 1980, the Philadelphia Water Department put an end to all ocean dumping by using the composting method to break down the waste, and by 1988 the Biosolids Recycling Center was established [1]. The establishment of the Biosolids Recycling Center was a huge step in eliminating wastewater pollution because of its ability to process wastewater from three plants that serve a total of 2.3 million people [1].
When Philadelphia was first established there were only a handful of residents living in the area. Because of this, they could easily dispose of their wastewater in the woods or somewhere out of the way. As the population grew, so did the amount of waste produced. At some point there was far too much waste to dispose of in the woods so the residents tossed it in the streams and rivers [2]. This method also proved to be acceptable for a period of time until the wastewater became so plentiful that it found its way into the resident’s water supply. At this point everyone realized that they needed to find an alternative method of disposing of their waste. The method they found to be practical was the disposal of wastewater into landfills which was a sufficient solution due to the small population at the time. This was also beneficial for the Philadelphians because it kept the hazardous wastewater out of the water supply.
Even with the disposal of wastewater into landfills the residents of Philadelphia ran into another problem. The landfills filled much faster then usual due to the additional load of wastewater. The solution was to use separate land for the disposal of wastewater instead of common trash landfills. This process allowed the liquid from the waste to seep into the ground. Eventually the waste would become dry and could be used on farmlands for fertilizer. This would have been an excellent solution if it weren’t for the toxins and bacteria that remained in the dried waste. These pollutants caused illnesses in people that ate the waste treated plants.
This method of treating wastewater continued for some time in Philadelphia until the opening of the Baxter Water Treatment Plant in 1909 [3]. The plant processes wastewater in order to make it drinkable again. It operates under strict guidelines from the government because the water is distributed amongst a large population. While treating the wastewater at the Baxter plant, the solids called sludge are collected and set aside. When the wastewater treatment plant was established there was no way to properly process the sludge so it was incinerated, dumped in the ocean or disposed of in landfills [4]. By 1988 the Philadelphia water department opened its sludge processing plant, known as the Biosolids Recycling Center (BRC), allowing this valuable resource to be used [1].
The establishment of the BRC turned out to be the new face of recycling. The Philadelphia Biosolids Recycling Center processes sludge from three different water treatment plants that currently serves 2.3 million people. As of 2008, the BRC program recycled 65 % of Philadelphia’s Biosolids [1]. Out of the 65% of Biosolids processed, 15% are used in coal mine reclamation, 25% in agricultural utilization, 20% in compost marketing, 10% in public works applications and 30% in landfill disposal.
The method of processing the Biosolids is actually a simple procedure. The BRC is housed on a 72 acre plot of land that houses dewatering centrifuges, aeration pads, aeration systems, sifters and specialized trucks [5]. The sludge is transported to the BRC by means of pipes or barges. Once the sludge has arrived it is dumped into the centrifuges in which the contents are spun so the water is forced out of the sludge mixture. The centrifuges in Philadelphia’s BRC are automated to allow for around the clock processing of the sludge material. These centrifuges process approximately 900 tons of sludge daily [5]. The water that is spun out of the sludge mix is collected and sent back to the water treatment plant so that it can be treated and returned back into a fresh water source [5].
Once the sludge has been dewatered it becomes a substance known as cake. The cake is taken to a different facility so that it can be made into compost. The cake is mixed with woodchips for the composting process. The compost mix is then transported to an aeration field in which it is separated into large piles. This field contains twenty seven 75-horsepower blowers that are positioned directly behind the compost mix [5]. These blowers pull air through the compost piles which draws air from the atmosphere through the piles. The air pulled in through the blowers is then sent to a filter to minimize the smell from the compost pile [5]. When the compost mix is sitting, the decomposition process creates heat and evaporation of moisture which kills all the pathogens within the compost. This natural process makes the compost mixture safe for agricultural usage. Once the mixture has sat for approximately a month it is taken to a large sifter that separates the processed cake from the woodchips which are reused in other composting mixtures [5].
The composting method utilized at the Philadelphia BRC is economically friendly in many ways. The waste that was once incinerated or dumped in the ocean is now recycled so it can be used in many applications throughout Philadelphia. Some more sophisticated BRC facilities even collect the gases given off from the composting process. These gases consist largely of methane which can be used to power the BRC facility [6].
Philadelphia’s world-leading BRC compost processing facility has greatly affected the amount of solids going to the landfills which are already brimming with the excess waste our society creates. Currently an average of 220,000 tons of cake are produced and distributed per year, 30% of which is still disposed of in landfills [1]. Other problems that can be alleviated from the use of cake are the enrichment of strip-mined land, crop production, eroded soil, and the forest [7].
The processed cake comes in two different grades know as Grade A and Grade B. The Grade A cake is processed a little more then Grade B which ensures that there is less risk of a pathogen. The Grade A cake is utilized mostly in the agricultural area where pathogen free cake is necessary. These agricultural companies grow the plants that are distributed amongst grocery stores in which we shop for food. Any kind of contaminant in these plants could cause wide spread illness throughout the city. Grade B cake is utilized among the strip-mined land in West Pennsylvania. The strip-mined land is often abandoned once all the coal has been blown out of a mountain leaving, a large dirt pit were a mountain used to be. The introduction of cake to the soil will encourage vegetation growth to cover the scarred environment.
Cake can also be used in severely dry areas which are prone to extreme flooding. The EPA has conducted studies that show that the application of Biosolids Cake can be utilized to lessen or eliminate erosion of the soil. It has even been proven that the application of Biosolids to the surface of a dry dirt area can protect the quality of water that seeps into the ground. The EPA proved that the nutrients found within the Biosolids Cake are less water soluble than actual animal manure [7]. This fact shows that less of the nutrients, and possibly pathogens, will seep into the ground than with animal manure and fertilizers. Because of this, Philadelphians can be ensured that any agricultural companies supplying vegetation are more environmentally friendly then those that take advantage of animal manure and fertilizer.
As far as the regrowth of the forest, the nutrients in Biosolids can be beneficial towards the growth of certain vegetation in the environment. The Biosolids nutrients also help to grow tree’s faster which is beneficial when it’s utilized in logging yards. With the use of Biosolids in such logging yards, the loggers can come back more regularly to the site to cut down the newly grown trees. This type of cycle would cut back on the demand of trees which are typically cut down in the rainforest were endangered species depend on the forest cover for survival. As with forests, agricultural growing fields show similar growth patterns. These fields grow plants faster without using harmful chemical fertilizers that are potentially dangerous to the environment.
The utilization of Biosolids in certain applications is certainly an advantageous use of an otherwise unusable source. Without this technology, the sludge from wastewater would be tossed to the side in a landfill taking up usable space for other items that are biodegradable. Biosolids Cake is an excellent source of nutrients for agricultural functions as well as general environmental needs. The exploitation of this resource alleviates the strain of the publics demand for fertilizer quality goods, and also generates income that reduces the amount of money Philadelphians have to pay for their water bills. Overall the Biosolids Recycling Center in Philadelphia is a wonderful new technology in our great city that is helping to reduce pollutants introduced to the water and land, as well as space used up in city landfills.


Bibliography:

[1] "Biosolids Management Overview." Phila.gov. Philadelphia Water Department. 11 May 2009 <http://www.phila.gov/water /biosolid_recycle_cen.html>.


[2] "History of Biosolids." Biosolids.org. National Biosolids Partnership. 11 May 2009 <http://biosolids.org/docs/history%20of%20biosolids.pdf>.

[3] "Urban Water Cycle." Phila.gov. Philadelphia Water Department. 15 May 2009 <http://www.phila.gov/water/urban_water_cycle.html>.
[4] "Biosolids Processing." Binkleybarfield.com. Binkley & Barfield. 22 May 2009 <http://www.binkleybarfield.com/services/waste%20management/biosolids.htm>.

[5] "Composting Biosolids in Philadelphia." Mabiosolids.ort. Mid-Atlantic Biosolids Association. 20 May 2009 <http://www.mabiosolids.org/docs/26542.PDF>.
[6] "The Biosolids Recycling Story." Nwbiosolids.org. Northwest Biosolids Management Association. 1 June 2009 <http://www.nwbiosolids.org/Pubs/BiosolidsKioskFinal.pdf>.
[7] "Biosolids Benefits." Biosolids.com. Biosolids.com. 5 June 2009 <http://www.biosolids.com/benefits.html>.